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10#include <linux/types.h>
11#include <linux/ip.h>
12#include <linux/netfilter.h>
13#include <linux/module.h>
14#include <linux/skbuff.h>
15#include <linux/icmp.h>
16#include <linux/sysctl.h>
17#include <net/route.h>
18#include <net/ip.h>
19
20#include <linux/netfilter_ipv4.h>
21#include <net/netfilter/nf_conntrack.h>
22#include <net/netfilter/nf_conntrack_helper.h>
23#include <net/netfilter/nf_conntrack_l4proto.h>
24#include <net/netfilter/nf_conntrack_l3proto.h>
25#include <net/netfilter/nf_conntrack_core.h>
26#include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
27#include <net/netfilter/nf_nat_helper.h>
28#include <net/netfilter/ipv4/nf_defrag_ipv4.h>
29#include <net/netfilter/nf_log.h>
30
31int (*nf_nat_seq_adjust_hook)(struct sk_buff *skb,
32 struct nf_conn *ct,
33 enum ip_conntrack_info ctinfo);
34EXPORT_SYMBOL_GPL(nf_nat_seq_adjust_hook);
35
36static bool ipv4_pkt_to_tuple(const struct sk_buff *skb, unsigned int nhoff,
37 struct nf_conntrack_tuple *tuple)
38{
39 const __be32 *ap;
40 __be32 _addrs[2];
41 ap = skb_header_pointer(skb, nhoff + offsetof(struct iphdr, saddr),
42 sizeof(u_int32_t) * 2, _addrs);
43 if (ap == NULL)
44 return false;
45
46 tuple->src.u3.ip = ap[0];
47 tuple->dst.u3.ip = ap[1];
48
49 return true;
50}
51
52static bool ipv4_invert_tuple(struct nf_conntrack_tuple *tuple,
53 const struct nf_conntrack_tuple *orig)
54{
55 tuple->src.u3.ip = orig->dst.u3.ip;
56 tuple->dst.u3.ip = orig->src.u3.ip;
57
58 return true;
59}
60
61static int ipv4_print_tuple(struct seq_file *s,
62 const struct nf_conntrack_tuple *tuple)
63{
64 return seq_printf(s, "src=%pI4 dst=%pI4 ",
65 &tuple->src.u3.ip, &tuple->dst.u3.ip);
66}
67
68static int ipv4_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,
69 unsigned int *dataoff, u_int8_t *protonum)
70{
71 const struct iphdr *iph;
72 struct iphdr _iph;
73
74 iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph);
75 if (iph == NULL)
76 return -NF_DROP;
77
78
79
80 if (iph->frag_off & htons(IP_OFFSET))
81 return -NF_DROP;
82
83 *dataoff = nhoff + (iph->ihl << 2);
84 *protonum = iph->protocol;
85
86 return NF_ACCEPT;
87}
88
89static unsigned int ipv4_confirm(unsigned int hooknum,
90 struct sk_buff *skb,
91 const struct net_device *in,
92 const struct net_device *out,
93 int (*okfn)(struct sk_buff *))
94{
95 struct nf_conn *ct;
96 enum ip_conntrack_info ctinfo;
97 const struct nf_conn_help *help;
98 const struct nf_conntrack_helper *helper;
99 unsigned int ret;
100
101
102 ct = nf_ct_get(skb, &ctinfo);
103 if (!ct || ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY)
104 goto out;
105
106 help = nfct_help(ct);
107 if (!help)
108 goto out;
109
110
111 helper = rcu_dereference(help->helper);
112 if (!helper)
113 goto out;
114
115 ret = helper->help(skb, skb_network_offset(skb) + ip_hdrlen(skb),
116 ct, ctinfo);
117 if (ret != NF_ACCEPT) {
118 nf_log_packet(NFPROTO_IPV4, hooknum, skb, in, out, NULL,
119 "nf_ct_%s: dropping packet", helper->name);
120 return ret;
121 }
122
123 if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status)) {
124 typeof(nf_nat_seq_adjust_hook) seq_adjust;
125
126 seq_adjust = rcu_dereference(nf_nat_seq_adjust_hook);
127 if (!seq_adjust || !seq_adjust(skb, ct, ctinfo)) {
128 NF_CT_STAT_INC_ATOMIC(nf_ct_net(ct), drop);
129 return NF_DROP;
130 }
131 }
132out:
133
134 return nf_conntrack_confirm(skb);
135}
136
137static unsigned int ipv4_conntrack_in(unsigned int hooknum,
138 struct sk_buff *skb,
139 const struct net_device *in,
140 const struct net_device *out,
141 int (*okfn)(struct sk_buff *))
142{
143 return nf_conntrack_in(dev_net(in), PF_INET, hooknum, skb);
144}
145
146static unsigned int ipv4_conntrack_local(unsigned int hooknum,
147 struct sk_buff *skb,
148 const struct net_device *in,
149 const struct net_device *out,
150 int (*okfn)(struct sk_buff *))
151{
152
153 if (skb->len < sizeof(struct iphdr) ||
154 ip_hdrlen(skb) < sizeof(struct iphdr))
155 return NF_ACCEPT;
156 return nf_conntrack_in(dev_net(out), PF_INET, hooknum, skb);
157}
158
159
160
161static struct nf_hook_ops ipv4_conntrack_ops[] __read_mostly = {
162 {
163 .hook = ipv4_conntrack_in,
164 .owner = THIS_MODULE,
165 .pf = NFPROTO_IPV4,
166 .hooknum = NF_INET_PRE_ROUTING,
167 .priority = NF_IP_PRI_CONNTRACK,
168 },
169 {
170 .hook = ipv4_conntrack_local,
171 .owner = THIS_MODULE,
172 .pf = NFPROTO_IPV4,
173 .hooknum = NF_INET_LOCAL_OUT,
174 .priority = NF_IP_PRI_CONNTRACK,
175 },
176 {
177 .hook = ipv4_confirm,
178 .owner = THIS_MODULE,
179 .pf = NFPROTO_IPV4,
180 .hooknum = NF_INET_POST_ROUTING,
181 .priority = NF_IP_PRI_CONNTRACK_CONFIRM,
182 },
183 {
184 .hook = ipv4_confirm,
185 .owner = THIS_MODULE,
186 .pf = NFPROTO_IPV4,
187 .hooknum = NF_INET_LOCAL_IN,
188 .priority = NF_IP_PRI_CONNTRACK_CONFIRM,
189 },
190};
191
192#if defined(CONFIG_SYSCTL) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
193static int log_invalid_proto_min = 0;
194static int log_invalid_proto_max = 255;
195
196static ctl_table ip_ct_sysctl_table[] = {
197 {
198 .ctl_name = NET_IPV4_NF_CONNTRACK_MAX,
199 .procname = "ip_conntrack_max",
200 .data = &nf_conntrack_max,
201 .maxlen = sizeof(int),
202 .mode = 0644,
203 .proc_handler = proc_dointvec,
204 },
205 {
206 .ctl_name = NET_IPV4_NF_CONNTRACK_COUNT,
207 .procname = "ip_conntrack_count",
208 .data = &init_net.ct.count,
209 .maxlen = sizeof(int),
210 .mode = 0444,
211 .proc_handler = proc_dointvec,
212 },
213 {
214 .ctl_name = NET_IPV4_NF_CONNTRACK_BUCKETS,
215 .procname = "ip_conntrack_buckets",
216 .data = &nf_conntrack_htable_size,
217 .maxlen = sizeof(unsigned int),
218 .mode = 0444,
219 .proc_handler = proc_dointvec,
220 },
221 {
222 .ctl_name = NET_IPV4_NF_CONNTRACK_CHECKSUM,
223 .procname = "ip_conntrack_checksum",
224 .data = &init_net.ct.sysctl_checksum,
225 .maxlen = sizeof(int),
226 .mode = 0644,
227 .proc_handler = proc_dointvec,
228 },
229 {
230 .ctl_name = NET_IPV4_NF_CONNTRACK_LOG_INVALID,
231 .procname = "ip_conntrack_log_invalid",
232 .data = &init_net.ct.sysctl_log_invalid,
233 .maxlen = sizeof(unsigned int),
234 .mode = 0644,
235 .proc_handler = proc_dointvec_minmax,
236 .strategy = sysctl_intvec,
237 .extra1 = &log_invalid_proto_min,
238 .extra2 = &log_invalid_proto_max,
239 },
240 {
241 .ctl_name = 0
242 }
243};
244#endif
245
246
247
248
249
250static int
251getorigdst(struct sock *sk, int optval, void __user *user, int *len)
252{
253 const struct inet_sock *inet = inet_sk(sk);
254 const struct nf_conntrack_tuple_hash *h;
255 struct nf_conntrack_tuple tuple;
256
257 memset(&tuple, 0, sizeof(tuple));
258 tuple.src.u3.ip = inet->rcv_saddr;
259 tuple.src.u.tcp.port = inet->sport;
260 tuple.dst.u3.ip = inet->daddr;
261 tuple.dst.u.tcp.port = inet->dport;
262 tuple.src.l3num = PF_INET;
263 tuple.dst.protonum = sk->sk_protocol;
264
265
266 if (sk->sk_protocol != IPPROTO_TCP && sk->sk_protocol != IPPROTO_SCTP) {
267 pr_debug("SO_ORIGINAL_DST: Not a TCP/SCTP socket\n");
268 return -ENOPROTOOPT;
269 }
270
271 if ((unsigned int) *len < sizeof(struct sockaddr_in)) {
272 pr_debug("SO_ORIGINAL_DST: len %d not %Zu\n",
273 *len, sizeof(struct sockaddr_in));
274 return -EINVAL;
275 }
276
277 h = nf_conntrack_find_get(sock_net(sk), &tuple);
278 if (h) {
279 struct sockaddr_in sin;
280 struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
281
282 sin.sin_family = AF_INET;
283 sin.sin_port = ct->tuplehash[IP_CT_DIR_ORIGINAL]
284 .tuple.dst.u.tcp.port;
285 sin.sin_addr.s_addr = ct->tuplehash[IP_CT_DIR_ORIGINAL]
286 .tuple.dst.u3.ip;
287 memset(sin.sin_zero, 0, sizeof(sin.sin_zero));
288
289 pr_debug("SO_ORIGINAL_DST: %pI4 %u\n",
290 &sin.sin_addr.s_addr, ntohs(sin.sin_port));
291 nf_ct_put(ct);
292 if (copy_to_user(user, &sin, sizeof(sin)) != 0)
293 return -EFAULT;
294 else
295 return 0;
296 }
297 pr_debug("SO_ORIGINAL_DST: Can't find %pI4/%u-%pI4/%u.\n",
298 &tuple.src.u3.ip, ntohs(tuple.src.u.tcp.port),
299 &tuple.dst.u3.ip, ntohs(tuple.dst.u.tcp.port));
300 return -ENOENT;
301}
302
303#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
304
305#include <linux/netfilter/nfnetlink.h>
306#include <linux/netfilter/nfnetlink_conntrack.h>
307
308static int ipv4_tuple_to_nlattr(struct sk_buff *skb,
309 const struct nf_conntrack_tuple *tuple)
310{
311 NLA_PUT_BE32(skb, CTA_IP_V4_SRC, tuple->src.u3.ip);
312 NLA_PUT_BE32(skb, CTA_IP_V4_DST, tuple->dst.u3.ip);
313 return 0;
314
315nla_put_failure:
316 return -1;
317}
318
319static const struct nla_policy ipv4_nla_policy[CTA_IP_MAX+1] = {
320 [CTA_IP_V4_SRC] = { .type = NLA_U32 },
321 [CTA_IP_V4_DST] = { .type = NLA_U32 },
322};
323
324static int ipv4_nlattr_to_tuple(struct nlattr *tb[],
325 struct nf_conntrack_tuple *t)
326{
327 if (!tb[CTA_IP_V4_SRC] || !tb[CTA_IP_V4_DST])
328 return -EINVAL;
329
330 t->src.u3.ip = nla_get_be32(tb[CTA_IP_V4_SRC]);
331 t->dst.u3.ip = nla_get_be32(tb[CTA_IP_V4_DST]);
332
333 return 0;
334}
335
336static int ipv4_nlattr_tuple_size(void)
337{
338 return nla_policy_len(ipv4_nla_policy, CTA_IP_MAX + 1);
339}
340#endif
341
342static struct nf_sockopt_ops so_getorigdst = {
343 .pf = PF_INET,
344 .get_optmin = SO_ORIGINAL_DST,
345 .get_optmax = SO_ORIGINAL_DST+1,
346 .get = &getorigdst,
347 .owner = THIS_MODULE,
348};
349
350struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4 __read_mostly = {
351 .l3proto = PF_INET,
352 .name = "ipv4",
353 .pkt_to_tuple = ipv4_pkt_to_tuple,
354 .invert_tuple = ipv4_invert_tuple,
355 .print_tuple = ipv4_print_tuple,
356 .get_l4proto = ipv4_get_l4proto,
357#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
358 .tuple_to_nlattr = ipv4_tuple_to_nlattr,
359 .nlattr_tuple_size = ipv4_nlattr_tuple_size,
360 .nlattr_to_tuple = ipv4_nlattr_to_tuple,
361 .nla_policy = ipv4_nla_policy,
362#endif
363#if defined(CONFIG_SYSCTL) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
364 .ctl_table_path = nf_net_ipv4_netfilter_sysctl_path,
365 .ctl_table = ip_ct_sysctl_table,
366#endif
367 .me = THIS_MODULE,
368};
369
370module_param_call(hashsize, nf_conntrack_set_hashsize, param_get_uint,
371 &nf_conntrack_htable_size, 0600);
372
373MODULE_ALIAS("nf_conntrack-" __stringify(AF_INET));
374MODULE_ALIAS("ip_conntrack");
375MODULE_LICENSE("GPL");
376
377static int __init nf_conntrack_l3proto_ipv4_init(void)
378{
379 int ret = 0;
380
381 need_conntrack();
382 nf_defrag_ipv4_enable();
383
384 ret = nf_register_sockopt(&so_getorigdst);
385 if (ret < 0) {
386 printk(KERN_ERR "Unable to register netfilter socket option\n");
387 return ret;
388 }
389
390 ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_tcp4);
391 if (ret < 0) {
392 printk("nf_conntrack_ipv4: can't register tcp.\n");
393 goto cleanup_sockopt;
394 }
395
396 ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udp4);
397 if (ret < 0) {
398 printk("nf_conntrack_ipv4: can't register udp.\n");
399 goto cleanup_tcp;
400 }
401
402 ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_icmp);
403 if (ret < 0) {
404 printk("nf_conntrack_ipv4: can't register icmp.\n");
405 goto cleanup_udp;
406 }
407
408 ret = nf_conntrack_l3proto_register(&nf_conntrack_l3proto_ipv4);
409 if (ret < 0) {
410 printk("nf_conntrack_ipv4: can't register ipv4\n");
411 goto cleanup_icmp;
412 }
413
414 ret = nf_register_hooks(ipv4_conntrack_ops,
415 ARRAY_SIZE(ipv4_conntrack_ops));
416 if (ret < 0) {
417 printk("nf_conntrack_ipv4: can't register hooks.\n");
418 goto cleanup_ipv4;
419 }
420#if defined(CONFIG_PROC_FS) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
421 ret = nf_conntrack_ipv4_compat_init();
422 if (ret < 0)
423 goto cleanup_hooks;
424#endif
425 return ret;
426#if defined(CONFIG_PROC_FS) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
427 cleanup_hooks:
428 nf_unregister_hooks(ipv4_conntrack_ops, ARRAY_SIZE(ipv4_conntrack_ops));
429#endif
430 cleanup_ipv4:
431 nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv4);
432 cleanup_icmp:
433 nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_icmp);
434 cleanup_udp:
435 nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udp4);
436 cleanup_tcp:
437 nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_tcp4);
438 cleanup_sockopt:
439 nf_unregister_sockopt(&so_getorigdst);
440 return ret;
441}
442
443static void __exit nf_conntrack_l3proto_ipv4_fini(void)
444{
445 synchronize_net();
446#if defined(CONFIG_PROC_FS) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
447 nf_conntrack_ipv4_compat_fini();
448#endif
449 nf_unregister_hooks(ipv4_conntrack_ops, ARRAY_SIZE(ipv4_conntrack_ops));
450 nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv4);
451 nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_icmp);
452 nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udp4);
453 nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_tcp4);
454 nf_unregister_sockopt(&so_getorigdst);
455}
456
457module_init(nf_conntrack_l3proto_ipv4_init);
458module_exit(nf_conntrack_l3proto_ipv4_fini);
459
460void need_ipv4_conntrack(void)
461{
462 return;
463}
464EXPORT_SYMBOL_GPL(need_ipv4_conntrack);
465
